An electric vehicle or a hybrid vehicle, for example, includes one or more batteries that supply electrical power to drive the vehicle. In one example, the batteries supply power to an electric motor to drive a shaft in the vehicle, which in turn drives the vehicle. The batteries may be drained and hence need to be charged from an external power source.
In general, power transfer systems are widely used to transfer power from a power source to one or more electric loads, such as for example, batteries in a vehicle. Typically, the power transfer systems may be contact based power transfer systems or contactless power transfer systems. In the contact based power transfer systems, components such as plug, socket connectors, and wires are physically coupled to the batteries. However, due to environmental impact, such connectors and wires may be affected. Further, establishing a physical connection between the power source and the batteries in the vehicle may involve cumbersome safety measures since high current and voltage are used for charging the batteries.
In the contactless power transfer systems, power converters are used to convert an input power to a transferrable power which is further transmitted to an electric load such as the batteries in a vehicle. The power converter includes switches which are operated at a particular operating/switching frequency to convert the input power to the transferrable power. Typically, depending upon the load, the operating/switching frequency of the power converter is changed to regulate or control an output voltage of the power transfer system. However, if the electric load is disconnected or varied, the output voltage of the power transfer system may attain a very high value in a very short time period. As a result, voltage gain of the power transfer system may also vary drastically. Such a sudden increase in the output voltage and/or drastic variation in the voltage gain may affect one or more components and operation of the power transfer system.
Therefore, there is a need for an improved system and method for actively controlling an output voltage of a wireless power transfer system without changing an operating frequency of the wireless power transfer system.